Pennyweight Conversion

Pennyweight, unit of measure

A pennyweight (dwt) is an obsolete unit of mass which is the same as 24 grains, 1/240th of a troy pound, 1/20th of a troy ounce, or approximately 1.555 grams. A penny coin was literally, as well as monetarily, 1/240th of a troy pound of sterling silver. The pennyweight lost its official status in the United Kingdom of Great Britain and Ireland in the Weights and Measures Act of 1878. Custom jewellers still use the pennyweight in their calculations for the necessary amount of precious metals in casting items using the lost wax process. While "dwt" is the most common abbreviation for pennyweight (as "d" was the abbreviation for "penny" in the pre-decimalisation British system), some sources list "pwt" as an alternative.